Yarn types refer to the various categories of yarn used in knitting and crocheting, each with unique characteristics. Common types include wool, cotton, acrylic, and blends. Wool is warm and elastic, making it ideal for winter garments, while cotton is breathable and perfect for summer projects. Acrylic is affordable and easy to care for, suitable for beginners. Yarn can also be classified by thickness, known as yarn weight. This ranges from lace (very thin) to bulky (thick), affecting the final appearance and texture of the finished item. Choosing the right yarn type and weight is essential for achieving the desired results in any project.